Internet Protocol (IP) is a communications protocol that provides an identification and location system for computers and networks and routes traffic across the Internet. Internet Protocol version 6 (IPv6) is a successor protocol over that implements several updates over Internet Protocol version 4 (IPv4).
IPv6 frames include control information (for addressing and routing) and a data payload. Further, the control information includes two distinct types of headers: a mandatory fixed length header and optional extension headers. Extension headers, introduced in IPv6, carry optional Internet Layer information and are placed between the fixed header and the upper-layer protocol header of an IPv6 frame. Each header forms a chain using “next header” fields. A “next header” field in the fixed header indicates the type of the first extension header (if any). The “next header” field of the last extension header indicates the type of the upper-layer protocol header in the payload of the frame.